Type classes that give a uniform interface to
storable signals, stateful signals, lists, fusable lists.
Some of the signal types require constraints on the element type.
Storable signals require Storable elements.
Thus we need multiparameter type classes.
In this module we collect functions
where the element type is not altered by the function.

This type is used for specification of the maximum size of strict packets.
Packets can be smaller, can have different sizes in one signal.
In some kinds of streams, like lists and stateful generators,
the packet size is always 1.
The packet size is not just a burden caused by efficiency,
but we need control over packet size in applications with feedback.

We could provide the LazySize by a Reader monad,
but we don't do that because we expect that the choice of the lazy size
is more local than say the choice of the sample rate.
E.g. there is no need to have the same laziness coarseness
for multiple signal processors.

Processor that shall be run in a feedback loop.
It's absolutely necessary that this function preserves the chunk structure
and that it does not look a chunk ahead.
That's guaranteed for processes that do not look ahead at all,
like map, crochetL and
all of type Causal.Process.